An electrically driven vehicle vacuum pump in a vehicle generates a negative pressure of 100 millibars absolute which is, for example, required to operate a pneumatic brake force booster and/or other pneumatically operated ancillary units independent of the operating state of an internal combustion engine. In an electric vehicle vacuum pump assembly, the electric output of the drive motor typically lies in the range of 100 W in the case of small vacuum pumps, and several 100 W in the case of large vacuum pumps. In the vacuum pump assembly, corresponding amounts of heat losses occur both in the drive motor and in the pump unit, the heat losses having to be reliably dissipated to prevent overheating, particularly of the drive motor. Depending on the pump output and the rotational speed of the pump unit, sound emissions may be such that extensive measures for sound attenuation and/or creating an acoustic barrier must be taken.
DE 199 36 644 A1 describes an electric vacuum pump assembly where the sound insulation measure is a simple cover at the discharge side of the pump unit.